The subject matter disclosed herein relates to refrigeration systems. More specifically, the subject matter disclosed herein relates to refrigeration of containers utilized to store and ship cargo.
A typical refrigerated cargo container, such as those utilized to transport cargo via sea, rail or road, is a container modified to include a refrigeration unit located at one end of the container. The refrigeration unit includes a compressor, condenser, expansion valve and evaporator coil, all located at the end of the container. A volume of refrigerant circulates throughout the refrigeration unit, and one or more evaporator fans of the refrigeration unit blow a flow of air across the evaporator coil cooling the air and forcing it out into the container.
The cooled air in typical container system is forced out of the refrigeration unit and along a floor of the container. As the cooled air travels away from the refrigeration unit, its temperature increases and it rises in the container and eventually returns to the refrigeration unit. This circulation of cool air from one end of the container to the other end and back again results in uneven cooling of the cargo in the container, since the air forced into the container gets warmer as it travels farther from the refrigeration unit. Further, the cargo positioned at a lower portion of the container will benefit more form the cooling flow than the cargo positioned at an upper portion of the container.
Additionally, the typical refrigeration system for a container is costly and occupies a large amount of space that would otherwise be available for loading cargo.